Abstract

The regulation of protein collection through pollen foraging plays an important role in pollination and in the life of bee colonies that adjust their foraging to natural variation in pollen protein quality and temporal availability. Bumble bees occupy a wide range of habitats from the Nearctic to the Tropics in which they play an important role as pollinators. However, little is known about how a bumble bee colony regulates pollen collection. We manipulated protein quality and colony pollen stores in lab-reared colonies of the native North American bumble bee, Bombus impatiens. We debut evidence that bumble bee colony foraging levels and pollen storage behavior are tuned to the protein quality (range tested: 17–30% protein by dry mass) of pollen collected by foragers and to the amount of stored pollen inside the colony. Pollen foraging levels (number of bees exiting the nest) significantly increased by 55%, and the frequency with which foragers stored pollen in pots significantly increased by 233% for pollen with higher compared to lower protein quality. The number of foragers exiting the nest significantly decreased (by 28%) when we added one pollen load equivalent each 5 min to already high intranidal pollen stores. In addition, pollen odor pumped into the nest is sufficient to increase the number of exiting foragers by 27%. Foragers directly inspected pollen pots at a constant rate over 24 h, presumably to assess pollen levels. Thus, pollen stores can act as an information center regulating colony-level foraging according to pollen protein quality and colony need.

Notes

Acknowledgements

We would like to thank David Holway, David Woodruff, Brian Johnson, and the anonymous reviewers for their comments on this manuscript. This research would not have been possible without our exceptional research assistants, Morgan Brown, Joseph Soriano, Pegah Tehrani, Gabriel Tran, Katie Dayton, Diana Chen, Christina Chou, Amy Havens, Jessica Parkyn, Jaemi Yi, Natalie Reed, and the ORBS (Opportunities for Research in the Behavioral Sciences) Program (NSF IBN 0316697).

References

Calderone NW, Johnson BR (2002) The within-nest behaviour of honeybee pollen forgers in colonies with a high or low need for pollen. Anim Behav 63:749–758CrossRefGoogle Scholar